ADF V2 natively supports decompression of files as documented at https://docs.microsoft.com/en-us/azure/data-factory/supported-file-formats-and-compression-codecs#compression-support. With this functionality ADF should change the extension of the file when it is decompressed so 1234_567.csv.gz would become 1234_567.csv however, I’ve noticed that this doesn’t happen in all cases.
In our particular case the file names and extensions of the source files are all uppercase and when ADF uploads them it doesn’t alter the file extension e.g. if I upload 1234_567.CSV.GZ I get 1234_567.CSV.GZ in blob storage rather than 1234_567.CSV.
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